Medically treating illnesses often requires delivering therapeutic fluid into various body compartments, such as the subcutaneous tissue. Diabetes mellitus patients, for example, require the administration of varying amounts of insulin throughout the day to control their blood glucose levels. Therapeutic fluid can be administered to the patient periodically as one or more daily fluid injections or continuously using infusion devices (e.g., an infusion pump). Subcutaneous injections are usually performed using a rigid (e.g., metal) hypodermic needle. Continuous fluid administrations are typically performed using a soft cannula that provides a passageway for fluid communication between, for example, subcutaneous tissue and an infusion device. A device that facilitates periodic (i.e., injections) and/or continuous fluid delivery without repeated needle or cannula insertion is described in International Publication No. WO 2009/016638 to Yodfat et al., the content of which is incorporated herein by reference in its entirety. Device embodiments described therein include a housing (also referred to as “mounting unit” or “mounting housing”) that may be initially adhered to the skin of a patient and a cannula securable to the housing that may be inserted through a passageway provided in the housing into a subcutaneous compartment within the patient. The cannula may be initially assembled with an insertion needle extending through the cannula. After piercing the skin, the insertion needle may be retracted leaving the cannula in place in the patient's body. A fluid delivery device (e.g., a standard syringe, injection pen or infusion pump) may be coupled to the cannula to establish fluid communication between the fluid delivery device and the body of the patient.
When the fluid delivery device is an infusion pump, it is typically coupled to the cannula by some type of tubing (e.g., lengthy tubing external to the pump). The housing, cannula and tubing components (used in conjunction with the infusion pump) are usually referred to collectively as an “infusion set,” as described, for example, in U.S. Pat. Nos. 4,755,173 to Konopka et al. and 5,522,803 to Teissen-Simony, the contents of which are incorporated herein by reference in their entirety. Infusion devices directly connectable to a housing without the use of tubing are disclosed, for example, in U.S. Patent Application Publication No. 2008/0215035 to Yodfat et al. and International Publication No. WO 2009/016638 to Yodfat et al., the contents of which are incorporated herein by reference in their entirety. Device embodiments disclosed in Publication No. 2008/0215035 include, for example, a skin-adherable housing configured as a cradle unit having a length and width substantially similar to that of the infusion device itself to facilitate removable connection of the infusion device to a patient. A connecting lumen provided in an outlet port of the infusion device may establish fluid communication between the device and a cannula connected to the cradle unit.
Another important aspect of medically treating and/or preventing illnesses includes the periodic and/or continuous monitoring or sensing of bodily analytes, such as glucose. Performing continuous and/or periodic sensing operations of bodily analytes within the interstitial fluid of the subcutaneous tissue is discussed, for example, in U.S. Pat. Nos. 5,390,671 to Lord et al. and 6,565,509 to Say et al., the contents of which are incorporated herein by reference in their entirety. Conventional sensing devices include a subcutaneous probe and a sensing unit that contains a processing unit. Insertion mechanisms and devices for subcutaneous probes are disclosed, for example, in U.S. Pat. No. 5,586,553 to Halili et al., the content of which is incorporated herein by reference in its entirety. The insertion set in Halili et al. includes a penetrating member extending through a mounting base adapted for seated mounting onto the patient's skin. A flexible probe includes a proximal segment carried by the mounting base and a distal segment protruding from the mounting base and having one or more electrodes thereon. When the mounting base is pressed onto the patient's skin, the penetrating member pierces the skin to subcutaneously place the probe's distal segment. The penetrating member can then be withdrawn from the mounting base, leaving the probe's distal segment within the patient's body. A device that facilitates both periodic and continuous sensing of a bodily analyte without repeated skin pricking is described, for example, in International Publication No. WO 2009/016638 to Yodfat et al.